#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<string.h>
#include<arpa/inet.h>
#include<sys/socket.h>
#include<pthread.h>
#define BUF_SIZE 1024
#define SMALL_BUF 100

void *request_handler(void *arg);
void send_data(FILE *fp,char *ct,char *file_name);
char *content_type(char *file);
void send_error(FILE *fp);
void error_handling(char *message);
//实现web服务器端，基于GET请求的
int main(int argc,char *argv[])
{
	int serv_sock,clnt_sock;
	struct sockaddr_in serv_adr,clnt_adr;
	int clnt_adr_size;
	char buf[BUF_SIZE];
	pthread_t t_id;
	if(argc!=3)
	{
		printf("Usage:%s<ip><port>\n",argv[0]);
		exit(1);
	}
	
	serv_sock=socket(PF_INET,SOCK_STREAM,0);
	memset(&serv_adr,0,sizeof(serv_adr));
	serv_adr.sin_family=AF_INET;
	serv_adr.sin_addr.s_addr=inet_addr(argv[1]);
	serv_adr.sin_port=htons(atoi(argv[2]));
	if(bind(serv_sock,(struct sockaddr*)&serv_adr,sizeof(serv_adr))==-1)
		error_handling("bind() error");
	if(listen(serv_sock,20)==-1)
		error_handling("listen() error");
	
	while(1)
	{
		clnt_adr_size=sizeof(clnt_adr);
		clnt_sock=accept(serv_sock,(struct sockaddr*)&clnt_adr,&clnt_adr_size);
		printf("Connection Request:%s:%d\n",inet_ntoa(clnt_adr.sin_addr),ntohs(clnt_adr.sin_port));
		pthread_create(&t_id,NULL,request_handler,&clnt_sock);
		pthread_detach(t_id);
	}
	close(serv_sock);
	return 0;
}
void *request_handler(void *arg)
{
	int clnt_sock=*((int*)arg);
	char req_line[SMALL_BUF];
	FILE *clnt_read;
	FILE *clnt_write;
	
	char method[10];
	char ct[15];
	char file_name[30];
	
	clnt_read=fdopen(clnt_sock,"r");
	clnt_write=fdopen(dup(clnt_sock),"w");
	//从clnt_read读取
	fgets(req_line,SMALL_BUF,clnt_read);
	//查找子字符串
	if(strstr(req_line,"HTTP/")==NULL)
	{
		send_error(clnt_write);
		fclose(clnt_read);
		fclose(clnt_write);
		return NULL;
	}
	strcpy(method,strtok(req_line," /"));
	strcpy(file_name,strtok(NULL," /"));
	strcpy(ct,content_type(file_name));
	if(strcmp(method,"GET")!=0)
	{
		send_error(clnt_write);
		fclose(clnt_read);
		fclose(clnt_write);
		return NULL;
	}
	fclose(clnt_read);
	send_data(clnt_write,ct,file_name);
	return NULL;
}
void send_data(FILE *fp,char *ct,char *file_name)
{
	char protocol[]="HTTP/1.0 200 OK\r\n";
	char server[]="Server:Linux Web Server \r\n";
	char cnt_len[]="Content-length:2048\r\n";
	char cnt_type[SMALL_BUF];
	char buf[BUF_SIZE];
	FILE *send_file;
	
	sprintf(cnt_type,"Content-type:%s\r\n\r\n",ct);
	send_file=fopen(file_name,"r");
	if(send_file==NULL)
	{
		send_error(fp);
		return;
	}
	//传输头信息
	fputs(protocol,fp);
	fputs(server,fp);
	fputs(cnt_len,fp);
	fputs(cnt_type,fp);
	//传输请求数据
	while(fgets(buf,BUF_SIZE,send_file)!=NULL)
	{
		fputs(buf,fp);
		fflush(fp);
	}
	fflush(fp);
	fclose(fp);
}
char *content_type(char *file)
{
	char extension[SMALL_BUF];
	char file_name[SMALL_BUF];
	strcpy(file_name,file);
	strtok(file_name,".");
	strcpy(extension,strtok(NULL,"."));
	
	if(!strcmp(extension,"html")||!strcmp(extension,"htm"))
		return "text/html";
	else
		return "text/plain";
}
void send_error(FILE *fp)
{
	char protocol[]="HTTP/1.0 400 Bad Request\r\n";
	char server[]="Server:Linux Web Server \r\n";
	char cnt_len[]="Content-length:2048\r\n";
	char cnt_type[]="Content-type:text/html\r\n\r\n";
	char content[]="<html><head><title>NETWORK</title></head>"
		"<body><font size=+5><br>发生错误！查看请求文件名和请求方式！"
		"</font></body></html>";
	fputs(protocol,fp);
	fputs(server,fp);
	fputs(cnt_len,fp);
	fputs(cnt_type,fp);
	fflush(fp);
}
void error_handling(char *message)
{
	fputs(message,stderr);
	fputc('\n',stderr);
	exit(1);
}
